text: In the present context, "incomplete transformation" refers to the fact that in the absence of carbide precipitation, the bainite reaction stops well before the austenite reaches its equilibrium or paraequilibrium chemical composition. It stops at the point where the free energies of austenite and ferrite of identical composition become the same, i.e. transformation without a change in chemical composition of the participating phases becomes thermodynamically impossible.
  Early research on bainite found that at a given temperature only a certain volume fraction of the austenite would transform to bainite with the remainder decomposing to pearlite after an extended delay. This was the case despite the fact that a complete austenite to pearlite transformation could be achieved at higher temperatures where the austenite was more stable. The fraction of bainite that could form increased as the temperature decreased. This was ultimately explained by accounting for the fact that when the bainitic ferrite formed the supersaturated carbon would be expelled to the surrounding austenite thus thermodynamically stabilising it against further transformation.